Ok. After being hit twice today about "high" chlorine in my pool I have to ask are there definititive studies other than experience that support the increasing ratio of CL related to CYA? Or any FB pool owners that have not had issues with following TFP recommended levels for their pools over the long term? I have a lighter colored rough textured film below the water line on my less than 2 year old fiberglass pool. I have used a saltwater generator and have really only been concerned with chlorine too low and never really worried about it if it's less than 10 as my pool person told me is considered "high" chlorine level. With that its been 5-8ppm most of the time. Of course I've done shocks occasionally and then post TFP- one slam. Over the winter I got lax on my maintenance and while the SWG was on 10% production, because of emergency trip on pump it ran 24 hours for many days. I realize it was running at night during low temps and scheduled for day. I didn't really pay attention to any levels for weeks at all. Even my pool store guy said not to worry about it too much because no one was in it. Now in researching I may have permanently damaged my gelcoat. Many theories but one that sticks out is combination high PH, high chlorine and low calcium. If low calcium is 175 or below they all apply to me in the winter. In addition, my pool installer adds that keeping alkalinity at 60-70 which is where mine had settled all summer per TFP can etch the coat as well. I see that winter mishap may have caused the problem and hope that it's just some slow to remove scaling as my water chemistry has been maintained since March. Explaining to both party's whom experience I respect about why I want to keep chlorine levels higher than recommended and their heads pop off. One says "free chlorine is free chlorine" The other says it's downright dangerous for pool material and swimmers with the ratios of chlorine for said CYA levels. I can only imagine that the pool manufacturer will laugh in my face about warranty on the coat in keeping my chlorine so much higher than their's recommends. I find it so ironic that FB pool manufacturers schtick is that they're so much easier to maintain and then the very first issue which is very distressing is that some chemical imbalance on your end caused the problem, I frankly have never heard gunite, plaster or liner experience where pool companies blame the customer so much and I very much regret going fiberglass right now.